Methylphenidate is a mild central nervous system stimulant that is believed to exert its effect through activation of the brain stem arousal system and cortex. Ritalin is used primarily to treat attention deficit disorders and narcolepsy. The drug has a stabilizing effect for children with behavioral syndromes such as distractibility, short attention span, hyperactivity, emotional ability, and impulsiveness. Diagnosis and treatment usually includes psychological, social, and educational factors along with the medication. Excessive doses of Ritalin over a prolong period can result in addiction, and it is also possible to develop tolerance to the drug, so that increased dosages are necessary to produce the desired effect. Side effects include nervousness, sleeplessness, abdominal pain, chest pain, dizziness, headaches, and hives.